bisecting fixing commit since c10b57a567e4333b9fdf60b5ec36de9859263ca2
building syzkaller on 2e44d63e401ead7d7928c95a30d243b2de1a243b
testing commit c10b57a567e4333b9fdf60b5ec36de9859263ca2 with gcc (GCC) 8.1.0
kernel signature: 27fc74b3aa4e1cde663a80ca279f3775336391dccc0c6404e34e7f7d1efb5fd1
run #0: crashed: divide error in fbcon_init
run #1: crashed: divide error in fbcon_init
run #2: crashed: divide error in fbcon_init
run #3: crashed: divide error in fbcon_init
run #4: crashed: divide error in fbcon_init
run #5: crashed: divide error in fbcon_init
run #6: crashed: divide error in fbcon_init
run #7: crashed: divide error in fbcon_init
run #8: crashed: divide error in fbcon_init
run #9: OK
testing current HEAD a41ba30d9df20fe141c92aacbb56b6b077f19716
testing commit a41ba30d9df20fe141c92aacbb56b6b077f19716 with gcc (GCC) 8.1.0
kernel signature: 19c1adf80d26c9101b2996700646e4d523b6ed4e321fbfda8483206e5521d90b
run #0: crashed: divide error in fbcon_init
run #1: crashed: divide error in fbcon_init
run #2: crashed: divide error in fbcon_init
run #3: crashed: divide error in fbcon_init
run #4: crashed: divide error in fbcon_init
run #5: crashed: divide error in fbcon_init
run #6: OK
run #7: OK
run #8: OK
run #9: OK
revisions tested: 2, total time: 39m55.40380815s (build: 17m37.4706067s, test: 21m45.898866853s)
the crash still happens on HEAD
commit msg: Linux 4.14.181
crash: divide error in fbcon_init
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 00007f30e53997d0
RBP: 000000000078bf00 R08: 0000000000000000 R09: 000000000000000e
R10: 0000000000000064 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000c0f R14: 00000000004ce39b R15: 00007f30e539a6d4
tty tty23: ldisc open failed (-12), clearing slot 22
divide error: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 7911 Comm: syz-executor.4 Not tainted 4.14.181-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88809f0a4180 task.stack: ffff888097410000
RIP: 0010:fbcon_init+0x6f5/0x1ee0 drivers/video/fbdev/core/fbcon.c:1116
RSP: 0018:ffff888097417688 EFLAGS: 00010246
RAX: 0000000000000280 RBX: ffff888096094600 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 1ffff11012c12936 RDI: ffff8880960949b4
RBP: ffff888097417720 R08: ffffffff8a4407c0 R09: 00000000000001e0
R10: ffff888096094934 R11: ffff888096094938 R12: ffff8880a5fb04c0
R13: 000000000000001c R14: ffff8880a5edba40 R15: ffff8880a5edbbf8
FS:  00007f39e27dc700(0000) GS:ffff8880aec00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4279542000 CR3: 000000009b0e4000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 visual_init+0x314/0x5d0 drivers/tty/vt/vt.c:746
 vc_allocate+0x2d5/0x5c0 drivers/tty/vt/vt.c:793
 con_install+0x4d/0x4c0 drivers/tty/vt/vt.c:2892
 tty_driver_install_tty drivers/tty/tty_io.c:1225 [inline]
 tty_init_dev+0xdb/0x350 drivers/tty/tty_io.c:1338
 tty_open_by_driver drivers/tty/tty_io.c:1973 [inline]
 tty_open+0x50a/0x970 drivers/tty/tty_io.c:2021
 chrdev_open+0x1e9/0x5b0 fs/char_dev.c:423
 do_dentry_open+0x620/0xdb0 fs/open.c:777
 vfs_open+0xfc/0x240 fs/open.c:888
 do_last fs/namei.c:3428 [inline]
 path_openat+0xdde/0x3bd0 fs/namei.c:3569
 do_filp_open+0x16b/0x220 fs/namei.c:3603
 do_sys_open+0x1c2/0x340 fs/open.c:1081
 SYSC_open fs/open.c:1099 [inline]
 SyS_open+0x19/0x20 fs/open.c:1094
 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x416621
RSP: 002b:00007f39e27db7a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0000000000508e80 RCX: 0000000000416621
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 00007f39e27db7d0
RBP: 000000000078bf00 R08: 0000000000000000 R09: 000000000000000e
R10: 0000000000000064 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000c0f R14: 00000000004ce39b R15: 00007f39e27dc6d4
Code: 89 d0 48 ba 00 00 00 00 00 fc ff df 48 8b 75 b0 48 c1 ee 03 0f b6 14 16 84 d2 74 09 80 fa 03 0f 8e dc 11 00 00 31 d2 48 8b 7d 98 <f7> b3 b0 03 00 00 48 89 fa 48 c1 ea 03 41 89 c0 48 b8 00 00 00 
RIP: fbcon_init+0x6f5/0x1ee0 drivers/video/fbdev/core/fbcon.c:1116 RSP: ffff888097417688
---[ end trace af645124c5bc1cc1 ]---